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United States Patent |
5,573,614
|
Tilman
,   et al.
|
November 12, 1996
|
Method for stabilizing a plastic zipper during attachment to a film
Abstract
A method for stabilizing and aligning interlocked male and female profiles
of a plastic zipper strip during attachment of the strip to a polymeric
film requires the use of profiles having stabilizers, perhaps taking the
form of wedges. The stabilizers, disposed in pairs on each side of the
interlocked male and female members of the profiles, mechanically
cooperate with one another to maintain the profiles substantially parallel
to one another and incapable of rocking about a longitudinal axis. The
stabilizers on the male profile may be inboard, outboard or at the same
distance from the interlocked male and female members as their respective
stabilizers on the female profile. The facing surfaces of the stabilizers
may be inclined so as to provide a wedging action with respect to one
another.
Inventors:
|
Tilman; Paul A. (New City, NY);
Scott; Richmond M. (Pleasantville, NY);
Machacek; Zdenek (Nanuet, NY)
|
Assignee:
|
Minigrip, Inc. (Orangeburg, NY)
|
Appl. No.:
|
388621 |
Filed:
|
February 14, 1995 |
Current U.S. Class: |
156/66; 493/213; 493/215 |
Intern'l Class: |
B31B 001/90; B65B 033/24 |
Field of Search: |
156/66
493/212-215
24/399,400,576,587
383/63
|
References Cited
U.S. Patent Documents
4372793 | Feb., 1983 | Herz | 156/66.
|
4498939 | Feb., 1985 | Johnson | 156/66.
|
4791710 | Dec., 1988 | Nocek | 24/587.
|
4964739 | Oct., 1990 | Branson | 383/63.
|
5368394 | Nov., 1994 | Scott | 24/587.
|
Primary Examiner: Stemmer; Daniel
Attorney, Agent or Firm: Kane, Dalsimer, Sullivan, Kurucz, Levy, Eisele and Richard, LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part (CIP) of U.S. patent application Ser. No.
08/249,144, filed May 25, 1994, now U.S. Pat. No. 5,462,360 and of U.S.
patent application Ser. No. 08/337,569, filed Nov. 10, 1994, which in turn
is a continuation-in-part of application Ser. No. 08/174,273 filed on Dec.
28, 1993, now U.S. Pat. No. 5,368,394
Claims
What is claimed is:
1. A method for stabilizing and aligning interlocked male and female
profiles of a plastic zipper strip during attachment of the strip to a
polymeric film comprising the steps of:
providing a first profile having a first base with first and second
surfaces, said first profile having a male interlocking member and a pair
of first stabilizers, one on each of two sides of said male interlocking
member, on said first surface of said first base thereof;
providing a second profile having a second base with first and second
surfaces, said second profile having a female interlocking member and a
pair of second stabilizers, one on each of two sides of said female
interlocking member, on said first surface of said second base thereof;
joining said first and second profiles together by interlocking their
respective male and female interlocking members to bring each one of said
pair of first stabilizers on said first profile into a position
substantially adjacent to one of said pair of second stabilizers on said
second profile and to maintain said second surface of said first base
substantially parallel to said second surface of said second base; and
contacting each one of said pair of first stabilizers with its respective
one of said pair of second stabilizers while attaching said second
surfaces of said first and second bases of said first and second profiles,
respectively, to polymeric sheet material,
so that said sheet material will be attached thereto in a consistent and
uniform manner as a consequence of the substantial parallelism of said
second surfaces.
2. A method as claimed in claim 1 wherein each one of said pair of first
stabilizers is inward of its respective one of said pair of second
stabilizers with respect to said interlocked male and female interlocking
members.
3. A method as claimed in claim 2 wherein each one of said pair of first
stabilizers has a surface inclined inwardly with respect to said
interlocked male and female interlocking members and each one of said pair
of second stabilizers has a surface inclined outwardly with respect to
said interlocked male and female interlocking members, said inclined
surfaces of said first stabilizers being adjacent to said inclined
surfaces of their respective second stabilizers in order to provide a
wedging action therebetween.
4. A method as claimed in claim 1 wherein each one of said pair of second
stabilizers is inward of its respective one of said pair of first
stabilizers with respect to said interlocked male and female interlocking
members.
5. A method as claimed in claim 4 wherein each one of said pair of second
stabilizers has a surface inclined inwardly with respect to said
interlocked male and female interlocking members and each one of said pair
of first stabilizers has a surface inclined outwardly with respect to said
interlocked male and female interlocking members, said inclined surfaces
of said second stabilizers being adjacent to said inclined surfaces of
their respective first stabilizers in order to provide a wedging action
therebetween.
6. A method as claimed in claim 1 wherein each one of said pair of first
stabilizers and its respective one of said pair of second stabilizers are
equidistant from said interlocked male and female interlocking members.
7. A method as claimed in claim 6 wherein each one of said pair of first
stabilizers has an abutting surface and each one of said pair of second
stabilizers has an abutting surface, said abutting surfaces of said first
stabilizers being adjacent to said abutting surfaces of their respective
second stabilizers in order to provide an intimate abutting contact
therebetween.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to the art of reclosable plastic bags having
extruded zippers, and more particularly to a reclosable bag having
fastener profiles including wedge-shaped stops, which facilitate the
joining attachment of the fastener profiles and which determine the amount
of pull force required to open the bags. The fastener profiles are further
of a design which makes inadvertent opening of the bags less likely.
The present invention also relates to reclosable plastic bags requiring a
greater pull force to be opened from within than from without, and to a
method for substantially reducing the variance in the forces required to
open such bags from within and from without, as well as the consequent
variability in the ratio between those forces.
The present invention further relates to a method for stabilizing and
aligning the profiles of a plastic zipper during its attachment to a sheet
of polymeric film, such as that used to make reclosable bags.
2. Description of the Prior Art
Reclosable bags used, for example, for storing household foodstuffs are
typically made of polyethylene. As shown in U.S. Pat. No. 3,416,199 to
Imamura commonly assigned with the present invention, a reclosable bag may
be formed of two opposed walls equipped at the mouth with fastener
profiles. These profiles include a male profile attached to one wall and a
female profile on the other wall. The profiles are shaped so that, when
they are aligned and pressed together into an engaging relationship, they
form a continuous closure for the bag. The bag may be opened by pulling
the walls apart thereby separating the profiles. Various geometric shapes
and arrangements for such profiles are shown in U.S. Pat. Nos. Re. 28,969;
3,323,707; 4,212,337; 4,363,345; 4,561,108; and 4,812,056. In addition,
U.S. Pat. Nos. 4,736,496 and 5,012,561 disclose reclosable bags with
profiles and internal ribs adjacent to the profiles. U.S. Pat. No.
4,822,539 discloses a reclosable bag with interlocking profiles, internal
guiding ribs disposed adjacent to the profiles, and stabilizing beams
disposed on the outside surface of the bag wall. U.S. Pat. No. 3,338,285
discloses a reclosable bag having several parallel interlocking male and
female profiles. In general, the profiles must be such as to provide
relatively high resistance to opening from inside the bag while rendering
the bag relatively easy to open from the outside.
For the zipper to function properly, it is important that the zipper
components (i.e. the profiles and any wedges, beams, ribs or the like
provided to enhance the operation of the profiles) maintain their
alignment. The problem of maintaining the alignment of the components of
the zipper is exacerbated where the zipper is in string or strip form to
be heat sealed to a film material from which the body of the bag is to be
formed, since the heat necessary to fuse the zipper strip to the film
could distort the profiles or a zipper component. Heretofore, the problem
has been avoided by adding webs to the zipper strip to separate the
profiles (and components) from the point of attachment to the film. In
U.S. Pat. No. 4,673,383 a zipper strip is disclosed having fusible ribs on
its undersurface to minimize the heat to which the zipper is subjected. In
U.S. Pat. Nos. 4,691,372; 4,731,911; and 4,817,188, an adhesive layer is
provided on the base of the profile portion of the strip.
Another aspect of the problem of maintaining the alignment of the
components during heat-sealing to a film material is reflected in the
ability of the profiles to rock relative to one another about a
longitudinal axis because a male interlocking member may pivot within a
female interlocking member about such an axis. This ability to rock or
pivot presents an instability of the two profiles relative to one another
which may have an adverse effect on the quality of the heat-seal between
the profiles and the film material.
SUMMARY OF THE INVENTION
In view of the above, an objective of the present invention is to provide a
reclosable bag with improved closure means resistant to inadvertent
opening.
Another object is to provide such closure means in the form of a zipper
strip which may be heat-sealed to an associated film without distorting
the zipper profiles or any of the components of the zipper.
Yet another object of the present invention is to provide a method for
stabilizing and aligning interlocked male and female profiles of a plastic
zipper strip during attachment of the strip to a polymeric film to
eliminate or substantially reduce the freedom of the profiles to rock
relative to one another about a longitudinal axis and the consequent loss
of uniformity and consistency in the heat-seal between the profiles and
the polymeric film.
Other objectives and advantages of the invention will become apparent from
the following description. A reclosable bag constructed in accordance with
this invention includes a front wall and a rear wall joined to form an
enclosure with a mouth defined by wall edges at the top of the bag and
male and female profile means having male and female members for
selectively opening and closing said mouth. Stabilizer wedges are provided
on each of the male and female profile means. Specifically, a stabilizer
wedge is provided on each side of the male and female members on the male
and female profile means. The wedges keep the zipper parallel during the
application of the zipper to the film from which the bag is made and have
a stabilizing effect during the attachment process. Further, the wedge
action controls the force required to open the bag, and substantially
increases the inside resistance to opening pressure from the product
within the bag. Finally, the stabilizer provides the zipper as a whole
with a wide-track feel for the benefit of the consumer.
The profiles are provided on zipper strips heat-sealed to the front and
rear walls of the bag. To facilitate the heat-sealing, a layer of a
material having a lower melting temperature than the zipper strips and the
bag material is provided underlying at least a portion of the zipper strip
width so that the zipper may be heat-sealed to the bag walls at a
temperature sufficiently low to prevent distortion of the profiles or
wedges, or of the bag material. The lower-melting-point material may
underlie only a portion of the zipper width, so that a hinged connection
is provided between the zipper strip and bag wall. The lower-melting-point
material may, for example, be a high ethylene-vinyl acetate (EVA)
material, a high melt index (M.I.) material, a thermoplastic olefin (TPO)
copolymer or polypropylene-ethylene copolymer, or an ethylene methyl
acrylate (EMA) copolymer.
The use of a lower-melting-point material under only a portion of the
zipper may enable the manufacturer to fix the position of the seal of the
zipper strip to the bag wall in spite of any lateral shifting, or "float",
thereof permitted by the equipment used to manufacture the bags. Such is
accomplished by making the lower-melting-point material in a strip wider
than the "float" which may occur in the equipment. In that situation, the
lower-melting-point material will be melted by the sealing head,
regardless of any shift laterally relative thereto, and will ensure a seal
at a constant position on the profile.
The present method for stabilizing and aligning interlocked male and female
profiles of a plastic zipper strip during attachment of the strip to a
polymeric film includes the step of providing a first profile having a
first base with first and second surfaces. A male interlocking member and
a pair of first stabilizers, one on each side of the male interlocking
member, are provided on the first surface of the first base.
Also provided is a second profile having a second base with first and
second surfaces. A female interlocking member and a pair of second
stabilizers, one on each side of the female interlocking member, are
provided on the first surface of the second base.
When the first and second profiles are joined together by interlocking
their respective male and female interlocking members, each one of the
pair of first stabilizers on the first profile is brought into a position
substantially adjacent to one of the pair of second stabilizers on the
second profile. The adjacent ones of the first and second stabilizers on
each side of the interlocked male and female interlocking profiles
cooperate to maintain the second surface of the first base substantially
parallel to the second surface of the second base and to prevent the
profiles from rocking relative to one another about a longitudinal axis.
The first stabilizers may be inward of, outward of, or at the same
distance from the interlocked male and female interlocking profiles
compared to their respective second stabilizers.
Each one of the pair of first stabilizers is contacted with its respective
one of the pair of second stabilizers while the second surfaces of the
first and second bases of their respective profiles are attached to
polymeric sheet material, so that the sheet material will be attached to
the second surfaces in a consistent and uniform manner as a result of the
substantial parallelism of the second surfaces of the profiles brought
about by the mechanical cooperation between the stabilizers.
The present invention will now be described more completely with frequent
reference being made to the drawings identified hereinbelow.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a plan view of a reclosable bag constructed in accordance with
the present invention;
FIG. 2 shows an enlarged side sectional view of the bag opening;
FIG. 3 shows an enlarged side sectional view, analogous to that presented
in FIG. 2, of the bag being opened from the outside; and
FIG. 4 shows another enlarged side sectional view, analogous to that
presented in FIG. 2, of the bag being opened from the inside;
FIG. 5 shows an enlarged side sectional view of an alternative embodiment
of the bag of the present invention wherein an interlayer is utilized
between the bag walls and profile strips;
FIG. 6 shows an enlarged side sectional view of a further embodiment of the
bag of the present invention;
FIG. 7 is a cross-sectional view of an apparatus used to seal zipper
profiles to plastic sheet material;
FIGS. 8A, 8B and 8C show pull test conditions for measuring the force
required to open plastic bags from without;
FIGS. 9A, 9B and 9C show pull test conditions for measuring the force
required to open plastic bags from within;
FIG. 10 is a cross-sectional view of a pair of interlocked zipper profiles
of the prior art;
FIG. 11 is a cross-sectional view of a pair of interlocked zipper profiles
which may be used in the practice of the present invention;
FIG. 12 is a cross-sectional view of an alternate embodiment pair of
interlocked zipper profiles which may be used in the practice of the
present invention; and
FIG. 13 is a cross-sectional view of a third embodiment pair of interlocked
zipper profiles which may be used in the practice of the present invention
.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, and specifically to FIGS. 1 and 2, a
reclosable bag 10 constructed in accordance with this invention includes
front and rear walls 12,14 seamed along three edges thereby forming an
enclosure with an opening or mouth 16 along the top or fourth edge 18. The
bag 10 is preferably made of a thermoplastic material such as polyethylene
by extrusion. Attached to internal faces, walls 12 and 14 are male and
female profiles 20,22 respectively, which extend continuously from side to
side of the bag. The profile serves to close the bag opening 16 when they
are interlocked as shown in FIG. 2.
The male profile 20 includes an asymmetric arrowhead 24 which locks into a
channel 26 formed by two inwardly curved members 28 having inwardly
pointing stubs 30. The asymmetric arrowhead 24 is so called because its
two barbs are not mirror images of one another. Barb 32 has an acute edge,
while barb 34 has a rounded edge. Barb 34 is closer to the mouth 16 of the
bag 10 than barb 32.
The male profile 20 has two stabilizer wedges 36, which are on each side of
the asymmetric arrowhead 24 and are parallel thereto across the width of
the bag 10. The stabilizer wedges 36 are inclined toward one another and
toward asymmetric arrowhead 24.
In like manner, the female profile 22 has two stabilizer wedges 38, which
are on each side of the inwardly curved members 28 and are parallel
thereto across the width of the bag 10. The stabilizer wedges 38 are
inclined away from one another, or, at least, have surfaces facing the
inwardly curved members 28 which are inclined away from one another.
When the male and female profiles 20,22 are interengaged as shown in FIG.
2, stabilizer wedges 36 protrude to some preselected degree into the
spaces between the stabilizer wedges 38 and the inwardly curved members 28
on the female profile 22.
Bag 10 is normally opened by gripping edges 18 on the outside of the bag 10
and pulling them apart. In response to such action the lower stabilizer
wedges 36,38, which are toward the inside of the bag 10, as shown in FIG.
3, abut against one another. This braces the male profile 20 against the
female profile 22, and allows the rounded barb 34 of the asymmetric
arrowhead 24 to glide past its adjacent stub 30 to open the bag 10. The
force required to open the bag 10 may be preselected by appropriately
choosing the angles at which the surfaces of stabilizer wedges 36,38
contact one another.
The situation that would arise from an opening force from within the bag 10
is shown in FIG. 4. In response to such action, the upper stabilizer
wedges 36,38, which are toward the outside of the bag 10, as shown in FIG.
4, abut against one another. This again braces the male profile 20 against
the female profile 22, and hooks the acute barb 32 of the asymmetric
arrowhead 24 behind its adjacent stub 30 inhibiting the opening of the bag
10. The force required to open the bag 10 from within may be preselected
by appropriately choosing the angles at which the surfaces of stabilizer
wedges 36,38 contact one another.
Bag 10 may be generated unitarily, for example, by extruding the walls
12,14, and the profiles 20,22 integrally. Alternatively, the closures may
be extruded separately, and then may be bonded to sheets of bag forming
material at some stage in the bag forming operation.
The construction of the zippers shown in FIGS 5 and 6 is the same as that
described above except that in each case an intermediate layer 42 is
provided between the base 40 of the profile strips and the bag walls
12,14. The intermediate layer 42 comprises, at least in part, a material
having a lower melt temperature than the base of the profile strip and the
bag material. For example, the material of the intermediate layer 42 may
have a higher EVA content or a higher melt index. Thus, in FIG. 5, the
zipper and bag material may be formed of a relatively low melt index
material, such as a conventional polyethylene, whereas the intermediate
layer 42 may be formed of a high EVA content polyethylene, or may be
provided of a relatively high melt index polyethylene material such as
sold by Quantum Chemical Co. under the tradename NATR 201, the melt index
of the latter being 6 as compared with a melt index of 2 for the
conventional polyethylene resin from which the zipper is formed. Those of
ordinary skill in the art understand the melt index (M.I.) of a
thermoplastic material to be the amount, in grams, which can be forced
through an orifice of 0.0825 inch diameter when subjected to a force of
2160 grams in ten minutes at a temperature of 190.degree. C. under the
procedure set forth in ASTM Standard D-1238.
Those of ordinary skill in the art will also recognize that the inclusion
of intermediate layer 42 having a lower melting point than the base 40 of
the profile strips and the bag walls 12,14 may permit the profile strips
to be bonded to the bag walls 12,14 at a lower temperature than that which
would be required to bond them directly to one another. As a consequence,
distortion of the profile strips, caused by exposure to temperatures near
the melting point of the polyethylene from which they may be extruded, as
well as a thinning of the bags walls 12,14 in the areas where the bonding
is being carried out, may be avoided through the use of a
lower-melting-point intermediate layer of this type.
In the embodiment of FIG. 6, on the male profile side of the zipper the
lower-melting-point material 44 of the interlayer is provided behind only
a portion of the zipper carrying the male profile. The lower-melting-point
material 44 extends downwardly (i.e. toward the bag bottom) from the top
edge of the zipper substantially behind the top wedge 36. The lower
portion 46 of the interlayer (i.e. behind the male profile and bottom
wedge) is formed of a non-seal material (i.e. a material that will not
fuse to the bag wall at the temperature at which the top portion 44 of the
interlayer is fused to the bag wall). As a result the male profile strip
will be hinged to the bag wall to enhance the resistance to opening of the
bag from within the bag in the manner described in U.S. Pat. No.
4,430,070. The lower-melting-point material 48 of the female profile strip
is disposed behind the female profile and strips 50 formed of non-seal
material are provided above and below the female profile as shown. As
above, the lower-melting-point material 44,48 may be a high EVA material
or a high melt index material.
In general, interlayers of the variety shown in FIG. 6 may be used to
overcome the variability in the forces required to open reclosable plastic
bags caused by the floating of the zipper profiles laterally with respect
to the sealing heads in the apparatus commonly used to bond the zipper
profiles to plastic sheet material.
Reference is made to FIG. 7, which shows, in part, a pair of interlocked
zipper profiles like those shown in FIG. 6, although it should be
understood that the discussion to follow is applicable to zipper profiles
of any configuration.
When being bonded to bag walls 12,14, the interlocked male profile 20 and
female profile 22 shown in FIG. 6 are passed along a channel 60 between
two sealing heads 62,64. It will be recognized that FIG. 7 is a
cross-sectional view of the apparatus used to effect the bonding, and that
the profiles 20,22 and bag walls 12,14 are moving either toward or away
from the observer between the sealing heads 62,64. Slippery,
heat-resistant belts 66, of a material such as TEFLON.RTM., are disposed
and run between sealing head 62 and bag wall 12, and between sealing head
64 and bag wall 14 to ensure that the bag walls 12,14 will slip freely by
the sealing heads 62,64 at the high speeds at which the sealing apparatus
operates, and that any material of the bag walls 12,14 that may melt will
not accumulate on the sealing heads 62,64.
Because channel 60 must be wide enough to accommodate the female profile
22, bag wall 14 and a TEFLON.RTM. belt 66, as shown in FIG. 7, there will
inevitably be some lateral shifting, or "float", of the profiles 20,22
within the channel 60, as the profiles 20,22 move longitudinally therein
between the sealing heads 62,64. As a consequence, the sealing positions
of bag wall 12 to male profile 20, and of bag wall 14 to female profile 22
in the prior art tend to wander laterally across the male and female
profiles 20,22. As a consequence of this wandering, the forces required to
open the bags from within and from without tend to be nonuniform. This is
particularly true where only a portion of the width of the profiles 20,22
is to be bonded to their respective bag walls 12,14, as was the case in
FIG. 6.
However, the present invention provides a method for overcoming this
variability, which is often unacceptable to the end users of the bags
being produced. The key is to provide lower-melting-point material 44,48
in the regions where a bond is desired in a width such that, despite any
lateral shifting, or "float", of the profiles 20,22 within the channel 60,
a portion of the lower-melting-point material 44,48 is always adjacent to
its respective sealing head 62,64. In other words, lower-melting-point
material 44,48 is provided in greater widths than any "float" in either
lateral direction, so that the sealing heads 62,64 are always adjacent to
lower-melting-point material 44,48, melt it, and produce a bond which does
not wander longitudinally in a given bag, or from one bag to another.
Stated somewhat differently, the lower-melting point material 44,48
provides selectively placed preferential seal areas. When float or lateral
shifting of the profiles occurs, the bond is confined to the preferential
seal area. The non-seal areas, defined by portions 46,50, ensure that
bonding does not occur in those areas which will adversely effect the pull
test requirements for the pouch or package.
For purposes of illustration, reference will now be made to FIGS. 8A, 8B
and 8C, which show pull test conditions for measuring the force required
to open plastic bags from without, that is, from outside, corresponding to
an intentional opening by a consumer. FIGS. 8A, 8B and 8C represent the
conditions where the interlocked male and female profiles 20,22 have been
attached to the bag walls 12,14, respectively, by passing between sealing
heads 62,64 on the left side, center and right side of channel 60 in FIG.
7. In each case, the dashed lines above and below the interlocked male and
female zipper profiles 20,22 represent the positions of sealing heads
62,64. As such, FIGS. 8A, 8B and 8C represent the effect of the float of
the interlocked male and female zipper profiles 20,22 to the left and to
the right within channel 60.
Recalling that sealing head 62 only seals lower-melting-point material 44
to bag wall 12, and that sealing head 64 only seals lower-melting-point
material 48 to bag wall 14, it will be readily understood that, when point
72 of bag wall 12 and point 74 of bag wall 14 are pulled apart to conduct
the pull test from without, the results are substantially the same for
FIGS. 8A, 8B and 8C. That is because, in each case, point 72 pulls the
male profile 20 outwardly of its interlocking with female profile 22,
while point 74 pulls from behind the interlocking point between the male
and female profiles 20,22. In each case, the rounded portion of the
arrowhead of male profile 20 simply slips out of the channel in the female
profile 22.
In contrast, FIGS. 9A, 9B and 9C show pull test conditions for measuring
the force required to open plastic bags from within, that is, from inside
the bag, corresponding to an unintentional opening of the bag from inside.
Again, the dashed lines above and below the interlocked male and female
profiles 20,22 represent the positions of sealing heads 62,64. As such,
FIGS. 9A, 9B and 9C represent the effect of the float of the interlocked
male and female zipper profiles 20,22 to the left and to the right within
channel 60.
Recalling again that sealing head 62 only seals lower-melting-point
material 44 to bag wall 12, and that sealing head 64 only seals
lower-melting-point material 48 to bag wall 14, it will be readily
understood that, when point 82 of bag wall 12 and point 84 of bag wall 14
are pulled apart to conduct the pull test from within a bag, the results
are substantially the same for FIGS. 9A, 9B and 9C. That is because, in
each case, point 82 pulls the male profile 20 outwardly of its
interlocking with female profile 22, while point 84 pulls from behind the
interlocking point between the male and female profiles 20,22. In each
case, the acute portion of the arrowhead of male profile 20 ensures that
it remains locked within the channel in the female profile 22.
Now, turning to FIG. 10, a cross-sectional view of a pair of interlocked
zipper profiles of the prior art is shown to illustrate the problems which
may arise from the ability of the profiles to rock relative to one another
about a longitudinal axis. A male profile 102 comprises a male
interlocking member 104 on a first base 106, while a female profile 108
comprises a female interlocking member 110 on a second base 112. The first
base 106 and second base 112 are unstabilized and can rock about a
longitudinal axis perpendicular to the figure. This potential for rocking
has been observed to cause problems during the attachment of polymeric
film to the bases 106, 112, because they are not physically maintained
parallel to one another.
FIG. 11 shows one embodiment of a pair of interlocked zipper profiles which
may be used in the practice of the present invention A first profile 120
has a first base 122 with a first surface 124 and a second surface 126. A
male interlocking member 128 and a pair of first stabilizers 130, one on
each of the two sides of the male interlocking member 128, on the first
surface 124 of the first base 122.
A surface profile 140 has a second base 142 with a first surface 144 and a
second surface 146. A female interlocking member 148 and a pair of second
stabilizers 150, one on each of the two sides of the female interlocking
member 148, on the first surface 144 of the second base 142.
When the first profile 120 and the second profile 140 are joined to one
another as shown in FIG. 11 by interlocking male interlocking member 128
with female interlocking member 148, the second surface 126 of first base
122 and the second surface 146 of second base 142 are maintained in a
substantially parallel condition by first stabilizers 130 and second
stabilizers 150.
In FIG. 11, the first stabilizers 130 are inward of their respective second
stabilizers 150 with respect to the male interlocking member 128 and
female interlocking member 148. In FIG. 12, which shows an alternate
embodiment pair of interlocked zipper profiles which may be used in the
practice of the present invention, second stabilizers 160 are inward of
their respective first stabilizers 170 with respect to the male
interlocking member 172 and female interlocking member 174. And further,
in FIG. 13, which shows a third embodiment pair of interlocked zipper
profiles which may be used in the practice of the present invention, first
stabilizers 180 and second stabilizers 190 are equidistant from male
interlocking member 192 and female interlocking member 194.
In the first embodiment, that shown in FIG. 11, each of the first
stabilizers 130 has a surface 152 inclined inwardly with respect to the
interlocked male interlocking member 128 and female interlocking member
148. In like manner, each of the second stabilizers 150 has a surface 154
inclined outwardly with respect to the interlocked male and female members
128,148. The surfaces 152,154 are adjacent to one another and provide a
wedging action therebetween to maintain second surfaces 126,146 parallel
to one another.
In the second embodiment, which is shown in FIG. 12, each of the first
stabilizers 170 has a surface 176 inclined outwardly with respect to the
interlocked male interlocking member 172 and female interlocking member
174. In like manner, each of the second stabilizers 160 has a surface 162
inclined inwardly with respect to the interlocked male and female members
172,174. The surfaces 162,176 are adjacent to one another and provide a
wedging action therebetween to maintain second surfaces 164,178 parallel
to one another.
Finally, in the third embodiment, shown in FIG 13, each of the first
stabilizers 180 has an abutting surface 182 and each of the second
stabilizers 190 has an abutting surface 196. The surfaces 182,196 are
adjacent to one another when male interlocking member 192 is interlocked
with female interlocking member 194 to provide an abutting action
therebetween to maintain second surfaces 184,198 parallel to one another.
Obviously, numerous modifications may be made to this invention without
departing from its scope as defined in the appended claims.
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